E6
Honeywell
Communication Error Between Display Board and Main Control Board
Honeywell AC shows E6 and may not respond correctly to remote or control inputs.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Loose communication cable between display PCB and main PCB, Damaged ribbon cable or harness, Oxidized connectors, Failed display PCB or main PCB
How to Fix / Troubleshooting
Safety: Disconnect power before opening the control panel.
Steps:
- Power cycle: Unplug for 5–10 minutes, then plug back in. If E6 persists, continue.
- Access control panel: Remove the front bezel or top cover to expose the display/control PCB. Note screw locations and gently pry plastic clips.
- Inspect communication harness: Locate the multi-wire harness or ribbon cable running from the display PCB to the main control board. Check for pinched, cut, or burnt sections.
- Reseat connectors: Disconnect and reconnect both ends of the cable several times to clean contacts. Ensure connectors latch fully.
- Check for moisture or corrosion: If the unit has been exposed to high humidity or water, dry the boards thoroughly and clean light corrosion with isopropyl alcohol and a soft brush.
- Replace suspect board or cable: If the cable is damaged, replace it with a Honeywell-compatible harness. If E6 remains, substitute the display PCB first (often easier and cheaper). If still unresolved, the main control PCB likely needs replacement.
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Repair Difficulty
Hard
4/5
Required Part
Display Control Board or Communication Harness
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